"In my view Kevin Rudd is a leader that has really been discredited by his own conduct," he said.

"His colleagues sacked him because they judged him to be incapable as prime minister.

"Here's a man that really has done the Labor Party enormous damage, destabilised it, and is now wishing to present himself to the Australian people as the prime minister and as the incoming prime minister.

I respect Mr Corbett talking up his own business book and his business interests, that's a matter for him. Mr Murdoch does the same. But guess what, Australian voters make up their own minds.

Kevin Rudd

"I don't think the Australian people will cop that to be honest."

But Mr Rudd has brushed off the comments.

"I respect Mr Corbett talking up his own business book and his business interests," he told ABC Radio Melbourne.

"That's a matter for him. Mr Murdoch does the same.

"But guess what: Australian voters make up their own minds."

Doug Cameron calls on Roger Corbett to quit RBA board

Mr Corbett's office has told the ABC the businessman has been a member of the Liberal party for "several years".

While Mr Rudd has response has been relatively mild, one of his frontbenchers is calling for Mr Corbett to resign from his RBA board position.

"I just think trading on your position as a reserve bank board member, trading on your position as the chair of Fairfax and not disclosing that you're a paid-up member of the Liberal Party is outrageous," Senator Doug Cameron told ABC News 24.

"I'm calling on Roger Corbett to do the right thing and resign as a member of the Reserve Bank board.

"He should not be there when he's running an agenda for the Liberal party.

"He has been absolutely deceitful and he should resign."

Mr Rudd has instead moved to rebut the comments with a defence of Labor's record on the economy, particularly in light of Mr Corbett's former role as Woolworths chief executive officer.

He led the supermarket giant's expansion into poker machines, just as the Labor Government tried to crack down on them.

"When we look at the huge stimulus given to domestic consumption in our country, during the height of the global financial crisis, much of which flowed through to retail outlets, because 15 per cent of Australians have their jobs there," Mr Rudd said.

"I think outfits like that have benefitted enormously from the action of the Government just like they've benefited enormously from interest rates being at 60-year lows."

"You'd have to question whether part of his motivation for attacking Kevin Rudd also related to any concerns he has about the so-called duopoly of Woolworths and Coles remaining as it is or business as usual post election."

Greens leader Christine Milne says the timing of Mr Corbett's intervention just days before the election is extraordinary.

"I think if business leaders have a view that they intend to express, they should express it at the time, not wait until they think there's a certainty in terms of who they think is going to be in government," she said.

"[Because] they then, by their remarks, guarantee themselves access, that's exactly what goes on through the corporate sector."

Mr Corbett also touched on reports Mr Rudd was actively undermining his own party under the stewardship of former prime minister Julia Gillard.

He told Lateline that "had a terrible effect on Labor and probably put them in a position that they needed to enter into a coalition with the Greens which was a very limiting factor ... and they were destabilised".

Abbott will 'probably be a pretty good PM'

"I think he'll probably be a pretty good prime minister because he's a very sincere, nice type of human being," Mr Corbett said.

"And I think he'll be very dedicated, focused on the job. And we certainly need, in the economic times we're about to go into, some really good, clear leadership."

When asked if Mr Corbett's role on the RBA should dictate a position of public impartiality, Mr Abbott said the businessman had the right to speak out.

"I think Mr Corbett is entitled to say that he thinks that there are some policies which have been disastrous," the Opposition Leader said.

Surely we're not attempting to gag people just because they have a strong view about the need for better policy in this country?

Tony Abbott

"Surely we're not attempting to gag people just because they're senior business people?

"Surely we're not attempting to gag people just because they have a strong view about the need for better policy in this country?"

Prominent economist Saul Eslake said it was "refreshing" to see such a senior business leader "saying what he thinks".

"Business people are rarely that direct," he told ABC News Online.

"It's unusual for someone in his position to be as blunt."

Mr Corbett, who as such is in charge of newspapers The Age and The Sydney Morning Herald, also accused his main business rival Rupert Murdoch of doing "great damage" to the credibility of the media through the coverage in News Corp Australia newspapers.

"To be as strongly biased as News (Corp) have been in the last few months, I do think does great damage to the credibility of press, at just the time when the press needs to be highly respected as we go through this digital transition," he said.

During the campaign, News Corp's most popular paper, Sydney's The Daily Telegraph, has run two striking front pages calling for Mr Abbott to be prime minister.